Die Cast Pro - Pentax Information

Range of light measurement (Spotmatic II)

The exposure meter of the Spotmatic measures the brightness of the ground glass. Therefore, the meter should be turned on after you have focused your subject on the ground glass. The following table shows the range of the meter's light measurement, and should not be interpreted as the camera's total range of f/stop-shutter speed combinations. As you will note from the table below, with an ASA100 film, you may use any shutter speed from 1 sec. to 1/1000 sec. in combination with any aperture that will bring the meter needle to the midpoint in the viewfinder. The total range of the aperture settings is, of course, determined by the minimum and maximum apertures of the lens being used. For example, with the 50mm f/1.4 lens and ASA 100 film, an aperture from f/1.4 (the maximum aperture of this lens) to f/16 (the minimum aperture) may be used with any shutter speed from 1 sec. to 1/1000 sec. that will bring the meter needle to midpoint.

 

ASA

B

1

1/2

1/4

1/8

1/15

1/30/

1/60

1/125

1/250

1/500

1/1000

20

                 
  • 25

 

 

 

 

 

 

 

 

 

 

32

                   
  • 40
                   
  • 50
                     

64

                   
  • 80
                   

100

                     
  • 125
     

A

         
  • 160
               

200

               
  • 250
                 
  • 320
                 

400

                   
  • 500
                 
  • 640
                 

800

                   
  • 1000
                 
  • 1250
                 

1600

B

             
  • 2000
           
  • 2500
           

3200

                   

The area A (red area) indicates the reading range of the meter. The area B (white area) indicates that although the shutter speed index is black and the meter needle moves, the meter is NOT operating properly.

When the meter needle is centered with the shutter speed dial set at B using ASA 20~50 films, this indicates that the exact shutter speed required is 2 seconds. Please expose your picture for 2 seconds.

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